The idea behind this layout is to have an American Keyboard with accented vowels (for Italian) to avoid switching language on the Mac every time you switch form English to Italian and being able to get the advantages that comes with the American (ANSI) keyboard when you write in English, code, or just want to use keybaord shorcuts (most of which are based on the American Keybaord).
Some things I did, useful to you fi you want to have a look to the scheme or even replicate it for your language.